Color photography



April 5, 1938.

L: D. MANNE-S ET AL coLoR PHOTOGRAPHY Filed Feb. 27, 1935 SENSITIVEEMULS/0N LAYER (YELLOW) NERT LAYER CONTA/NIN@ YELLOIJ DYE SENSITIVEEMULS/ON LAYERMAGENTA) SENSITIVE EMULS/ON LAYER BLUE 'GREENI LA TENTBLUEIMAGE gvwmtom Lefoulzummw duomwc -Patented Apr. 5, 1938 COLORPHOTOGRAPHY Leopold D. Mannes and Leopold Godowsky, Jr.,

Rochester, N. Y., assignors, by mesne assignments, to Eastman KodakCompany, Jersey City, N. J., a corporation of New Jersey ApplicationFebruary 27, 1935, Serial No. 8,516

19 Claims.

'I'his invention relates to color photography and more particularly to aprocess in which a plurality of light-sensitive layers are treated toform a colored photographic record.

This application is a continuation-in-part of our application, SerialNumber 634,182, filed September 21, 1932, matured into U. S. Patent No.2,059,884, of November 3, 1936. i

It is known in. processes for producing colored l0 photographs in whicha plurality of layers of differently sensitized emulsions are treated toproduce a colored photographic record by simultaneously exposing the.layers, and then developing, fixing and coloring the resulting images invarious ways. It has been proposed to dye the sensitired emulsion layerprior to exposure and later to remove the dye at the image or non-imageportions. Processes have also been devised in which a dye-formingcompound is mixed with the emulsion layer and a dye formed upondevelopment. These processes all have numerous objectionable features,among which are the difficulties in processing and the inability of the`user to obtain satisfactory colors.

An object of the present invention is to produce a satisfactorilycolored photograph in two or more colors by simple and practicalprocedure. A further object is to produce a film adapted for takingpictures in' three colors in which no color- A ing matter orcolor-forming substances is mixed with the emulsion prior to exposure.Other objects and advantages will'be apparent from the followingdescription.

'I'hese objects are accomplished by' the following invention in whichthe colors are formed by a chemical coupling or dye formation, a dyebeing formed simultaneously and in situ with the development of theimage.

Reference will be had to the accompanying 40 drawingin which:

Fig. 1 is a sectional view of a film having three separate emulsionlayers;

Fig. 2 is a modified form of lm; Figs. 3, 4, 5 and 6 are sectional viewsof the film illustrating the condition of the emulsion layers at variousstages of the processing.

Fig. 'I is a sectional view of a finished lm having a sound trackrecorded in three layers. Y In practicing the invention we prefer to usea iilm of the type illustrated in Fig..1 in which I0 is the usual typeof transparent base such as cellulose nitrate or cellulose acetate. Thesensitized silver halide emulsions are' coated on one side of this basein three layers, the layer II coated next to the base being sensitive tored light, the intermediate layer I2 sensitiveto green light and the topor outermost layer I3 sensitive to blue light. These layers arepreferably'separated by layers of inert material such as gelatinillustrated at I4 and I5. The layer I5 may con- 5 tain a yellow dye inorder to filter out blue light and prevent it-from reaching the layersII and I2, which, while sensitive to red and green, are also sensitiveto blue light. This yellow dye may,

if desired, be'incorporated in the outer blue sen- 10 sitive layer I 3.

The layers II and I2 are the usual silver halide emulsion layerssensitized to red and green light, respectively, with sensitizing dyeswhich are well known in the art. A suitable red sensitizing dye 15 isnaphthocyanol, and a suitable green sensitizing dye is erythrosin.

The process may be considered as divided into a series of units, eachcomprising a number of steps, and we will designate these as units A, B,and C.

This film is exposed in the usual way to form an image and since nofilter is essential except that which is incorporated in the filmitself, a shorter exposure may be made than with colored filmsheretofore used. However, a lter may be used to overcome errors in thecolor ratio, or to produce special eects.

In treating the film after exposure a reversal development may be used,thus forming a posi- 30 tive picture directly or the film may bedeveloped as a negative and positives printed from it. An essentialfeature inthe processing is a differential treatmentV of the layers bymeans of which the outer layer I3 may be treated without aifect- 35 inglayers I I and I2 or the outer layers I2 and I3 may be treated withoutaffecting layer II. In order to aid in treating only the desired layers,the inert gelatine layers I4 and I5 are inserted between the sensitizedlayers to allow the opero ator some leeway. It has been found, however,that the differential treatment of the layers can be controlled withsuch a degree of accuracy that these inert layers are not absolutelynecessary and in Fig. 2 a modification of the film is illus- 45 tratedin which the sensitized emulsion layers are coated-directly one on topof the other.

The process will first be described with'reference to a reversaldevelopment. In using a film such as that illustrated, in which the baseis 50 coated with layers sensitive to three colors, the process stepsmay be divided into three separate units, at the end of each' of whichone of the layers is colored with the dye winch it finally retains.Referring to Figs. 3 to 6 the steps of 55 unit A will now be described.The illm after exposure contains latent images in each of the threeemulsion layers, I I, I2 and I3. These are illustrated in Fig. 3, I6being the latentv image corresponding to the red of the objectphotographed, I1 the latent image corresponding to the green and I8 thelatent image corresponding to the blue. The film is developed in an M-Qdeveloper, forming silver images I9, 20 and 2| corresponding,respectively, to the red, green and blue of the object photographed.

A suitable developer has the formula:`

The ilim is next washed and then bleached in a bath which removes thesilver but does not attack the silver halide present in each layer.

This bleach bath may have the followingcomposition:

Grams Potassium permanganate (4% solution).... 1 Sulfuric acid (20%solution) 1 Water 20 After the bleaching, the film is again washed, andthen subjected to a clearing bath oi sodium 0r potassium bisulfite orany other bath capable of removing from the lm the manganese compoundsor any other products that may have been formed in the bleachingoperation. The customary bath for this purpose is a 2% solution ofsodium bisulflte. The illm is again washed, and is then ready to beexposed. Each of these washing steps, as well as the clearing bath, iscarried out at 70 F. for about 4 minutes. The bleach bath is kept at aslightly lower temperature, about 65 F. f

The developer contains, in addition to the usual developer constituents,including a para-amino aniline as the developing agent, a coupling ordye-forming compound such as any of the hydroiw diphenyls described inmy copending application, Serial No. 8,520, led February 27, 1935,inatgred into U. S. Patent No. 2,039,730, of May A suitable developer isthe following:

(a) p-Amino diethyl aniline monohydrochloride g-- 3 Sodium sulfite g-- 5Sodium carbonate g-- 50 Potassium thiocyanate g-- 1/2 Water to cc 1000.(b) m-Hydroxy diphenyl g-- 21/2 Methyl alcohol." cc 100 (In use, b isadded to a) Since the oxidation illustrated at Fig.'6 and contains thethreelayer images consisting of metallic silver and blue-green dye at25, 26 and 21. The film is then xed to removel any residual silverhalide which may be present, washed, and thoroughly dried. Thiscompletes unit A.

The first step of unit B is the de-coloring of the dye in the outerlayers I2 and I3, and the re-conversion of the metallic silver in theselayers to silver halide. This may be done by the use of a bleach bathconsisting of a solution of quinone and concentrated hydrochloric acidcontaining a retardant such as glycerine and isopropyl alcohol tocontrol the depth of penetration of tlie bleach.

Such a bath may have the composition:

Glycerine cc 500 Iso-propyl alcohol cc 1000 Water cc 75 Quinone g-- 5Hydrochloric acid (conc.) g 20 Sodium bicarbonate g-- l5 Iso-propylalcohol cc 1000 Glycerine cc 1000 Water cc 1000 The stop bath which willbe used will depend, of course, upon the type of bleach bath used, analkaline stop bath being used to neutralize the action of the acidbleach bath. The dye contained in the outer layers I2 and I3 has nowbeen de-colorized and the silver converted to silver chloride at thepoints at which there was a bluegreen silver image at 26 and 21 in theselayers. The lm is then washed to insure removal of the de-colorized dyecompounds and is then redeveloped in a second color-forming developerwhich develops the silver chloride in the outer o layers I2 and I3 tometallic silver and forms a magenta dyev at the points at which thesilver is formed. Such a developer may contain as the color-formingcomponent p-nitro phenyl aceto nitrile, which couples with the oxidationproduct of the developer.

The magenta developer may have the following composition:

(a) 2-amino 5diethyl`amino toluene hy- (In use, b is added to a) Thefilm is now Washed and dried. A'I'his completes unit B, and the lm nowcontains a. blue-green image in the innermost layer II and magentaimages in the layers I2 and I3.

`As the first step in unit "C" the magenta. dye lcontained in the outerlayer I3 is bleached and the silver re-converted to silver halide. Thebath used for this purpose is similar to the bleach bath used in unit Balthough the treatment is for a shorter time, for example two minutes at72 to 74 F. The action of this bath is terminated by a stop bath as inthe case of unit B and the' (a) p-Amino dimethyl aniline sulfate g 1Sodium sulflte g 2 Sodium carbonate -g-.. 30 Water to cc-.. 1000 (b)4-nitro acetoacetanilide g 2% Iso-propyl alcohol cc (In use, b is addedto a.)

The film now contains a blue-green image in the inner layer Il, amagenta image in the intermediate layer I2 and a yellow image in theouter layer I3, together with metallic silver in each of the layers.'I'he metallic silver is removed in a suitable bath such as potassiumferricyanide solution, leaving the film as illustrated in Fig. 7 (wherea sound track is included), the emulsion layers now containingblue-green image 29 in the inner layer. magenta image 30 in theintermediate layer, and yellow image 3l in the outer layer. The film isthen washed and dried.

We have described our process employing a film in which the emulsionlayers are sensitized, from the base to the outer surface, to red,green, and blue light, respectively. 'I'he emulsion layers need not,however, be coated on the film in this order. For example, the greensensitive emulsion. might be coated next to the base.

If it is desired to produce a, negative from which positives may beprinted, the exposed film mayy be treated in various ways.

(1) The film is developed in an ordinary metolhydroquinone type ofdeveloper which may -have the same formula as that used for the firstdevelopment in the reversal processing. The film is ihen fixed to removeundeveloped silver halide and the remaining silver bleached to silverhalide, for example, in a hydrochloric acid oxidizing -bleach bath.. Thefilm is then color developed in a bluegreen color-developer having thesame formula as that referred to in the description of the reversaldevelopment process. This results in bluegreen negative images in eachof the three layers.

'I'he film is then processed as described above under units B and C. Thefilm then has negative blue-green, magenta, and yellow images in thethree layers.

(2) Instead of developing in an ordinary developer, the negative imagesmay be developed directly in a color forming developer. However,

when using this method excessive exposure seems to be necessary.Therefore, the use of a normal black and white photographic developerfor' initial negative development is preferable, giving maximumeffective speed in the camera. After this color development, the film istreated as described in units B and C above.

(3) 'I'he film containing thelatent images may lbe developed directly ina black and white photographic developer, fixed and bleached in dilutepotassium ferricyanide to convert the silver images to silverferrocyanide. This method is substantially the same as that describedunder method (l) above, except that the silver images are bleached tosilver ferricyanide rather than silver halide. This is sometimesdesirable because the silver ferrocyanide produced is very easilyreducible back to metallic silver. A suitable bleach for this purposeis:

Potassium ferricyanide grams-- 10 Ammonia- 28% solution cc 10 Water tocc-- 1000 The next step is the exposure and redevelopment of thebleached images in the color forming developer yielding insolublemonochrome dye images together with redeveloped silver. The images inthe outer layers are then bleached andI recolored as described aboveunder units B and C. The outer images are preferably bleached to silverhalide, although a ferricyanide bleach may be (4) An alternativeferricyanide method may be used and-while it involves more steps.thanmethod 3, it'has the advantage of minimizing any tendency to harden thegelatin in the image portions and, therefore, facilitates the attainmentof satisfactory balance between the emulsions throughout the usefuldensity range. By this method, the film is developed, fixed, Washed andbleached in potassium ferricyanide to convert the images in both layers.The film is then exposed and the top layer only redeveloped to silver bycontrolling the penetration of an energetic developer and arresting thedevelopment as soon as the desired depth is reached. This arrestingaction is attained by loading the developer solution with an arrestingagent, such as sodium sulphate. The following developer may be used:

Hydroquinone grams 12.5 Sodium sulflte do 19 Potassium hydroxide do 4lSodium sulfate do 200 Water to cc 1000 The action of this developingbath is arrested by immediate immersion in a stop bath, kept at very lowtemperature, for example'O" C. to 5 C. Such a stop bath is Sodiumsulfite grams- '50 Glacial acetic acid.l cc 30 Water to cc-- 1000 .Thesemethods of controlling and arresting the action of a bath-so astorestrict its effect to an upper stratum is the subject of co-pendingapplication, Serial No. 8,517,.led February 27,

` used together with an acid to decolorize the dye.

1935 matured into U. S. Patent No. `2,059,887 y of November 3, 1936.

At this stage of the processing, the-film contains a developable silverferrocyanide .image in the inner layer and metallic silver images in theouter'layers. The film is immersed in a bluegreen color formingdeveloper and the image in the inner layer developed to silver andbluegreen dye. The silver images in the outer layers are, of course,`inert to the color forming developer. 'The silver `images in the outerlayers mayl then be bleached in a potassium ferricyanide bath, thediffusion being controlled in the manner described in our saidco-pending application SerialNo. 8,517, matured into U. S. Patent No.2,059,887 of November 3, 1936, to prevent its action on the dyeimage intheinner layer. The silver ferrocyan'ide images in the or more dyes.

outer layers may then be color developed to a single color and the outerlayer only bleached and recolored, or the outer layer only may beredeveloped to silver and the intermediate layer then color developed bycontrolled penetration, and the outer layer nally converted to a silversalt and color developed.

In the negative processing the dyes used in addition to having theproperty of being easily bleached in the chromic acid, or other bleachby controlling the spectral transmission of the light used for recordingthe sound track on thel finished print, so that the track is recordedonly on the layer or layers sensitive to light of the color used. It ispossible to allow the sound track in the various layers to bleach and color develop along with the development of the picture portion. or thesound track may be formed of one color in one or more of the layers andthe sound track portion of the illmvarnished before the illm is -treatedin subsequent treatment baths in order tolimit the sound track toasingle color. Fig. 7 shows a multilayer lm in which the base I l carriesthe three emulsion layers Il, I2 and Il in which an image is recordedand also having a sound track portion 28 having the sound recorded inthree layers.

We have described our process as adapted to the lformation of threecolor component images, since a better,` reproduction of color may be.

obtained in this way. It is apparent, however, that the process is alsoapplicable to the formationof two color component images by treating twodiierentially sensitized emulsion layers by the methods described. Wheretwo colors only areused, the emulsion layers are sensitized withsuitable color separation dyes, such as blue-green and red-orange.

. Various other modications of the process may' be used. Numerous colorforming compounds are suitable, as well as' various bleach and stopbaths.v The emulsion layers may be coated on a paper or other support aswell as on the trans- `parent illms and plates described. Numerous othermodiilcations and variations of the process not herein specifica/ilydescribed are available arid-we intend to be limited only as we arerestricted by the appended claims.

What we claim is:

1. The process of producing a colored photographic record on a sensitiveelement having a plurality of superposed, differently sensitized silyver halide layers, which comprises simultaneously forming latent imagesin the layers, the images being dierent .color sensation records of asubject, simultaneouslysdeveloping the latent images to metallic silverimages, bleaching the images to remove the silver, exposing thesensitive element to light, redeveloping the images' in a color-formingdeveloper, selectively bleaching at least the outer layer andredeveloping said last mentioned layer in a developer.

2. 'I'he process of producing a colored photographic .record on asensitive element having three superposed, differently sensitized silverhalide layers, which comprises simultaneously forming latent images inthe layers, the images being different color sensation records of asubject, simultaneously developing the latent images to metallic silverimages, bleaching the images to remove the silver, exposing thesensitive element to light, ,redeveloping the images in a coloriormingdeveloper, selectively bleaching the two outer layers, redeveloping thetwo outer layers in a second color-forming developer, bleaching theouter layer and redeveloping it in a third color-forming developer.

3. 'Ihe process of producing a colored photographic record on asensitive element having a plurality of superposed, diierentlysensitized silver halide layers, which comprises simultaneously forminglatent images in the layers, the images being diiIerent color sensationrecords of a subject, simultaneously developing the latent images tometallic silver images, bleaching the images to remove the silver,exposing the sensitive element to`light, redeveloping the images in acolor-forming developer in which a color second color-forming is formedsimultaneously and in situ with development of a silver image.selectively bleaching at least the outer layer and redeveloping saidlast mentioned layer in a second color forming developer.

4. 'I'he process of producing a colored photographic record on asensitive element having a plurality of superposed. diilerentlysensitized silver halide layers, which comprises simultaneously forminglatent images in the layers, the images being different color sensationrecords of a subject, simultaneously developing the latent images tometallic silver images, bleaching the images toremove the silver,exposing the sensitive element to light, redeveloping the images in acolor-iormlngdeveloper in which a`color is formed by chemical couplingof a color-forming compound presenti 'the developer with an oxidationproduct of' the developer, selectively bleaching at least the outerlayer and redeveloping said last-mentioned layer in a secondcolor-forming developer.

5. The process of producing a colored photo? veloper, ilxing out theunexposed silver halide,-

selectively bleaching at least the outer layer and redeveloping saidlast mentioned layer in a colorforming developer.

6. 'I'he process of producing a colored photographic record on asensitive element having a plurality of superposed differentlysensitized silver halide layers which comprises simultaneously exposingfrom the same .side to form latent images in the layers, the imagesbeing different color sensation records of a subject, simultaneouslydeveloping the latent images to metallic silver and dye images by meansof a color-formingdeveloper in which a color is formed by chemicalcoupling of a color-forming compound present in the developer with anoxidation product ot fix the developer, ilxing out the unexposed silverhalide, selectively bleaching at least the outer layer and redevelopingsaid last mentioned layer in a color-forming developer.

7'. The process of producing a sound track on a sensitive element havinga plurality of ysuperposed differently sensitized, silver halide layerswhich comprises forming a latent image of the sound track in each layer,developing said 1atent images to metallic silver, bleaching the imagesto remove the silver, exposing the sensitive element to light,redeveloping the images in a color-forming developer, selectivelybleaching at least the image in the outer layer, and redeveloping saidlast-mentioned layer in a second color-forming developer.

8. The process of producing a sound track on a sensitive element .havinga plurality of superposed, differently-sensitized, silver halidelayerswhich comprises forming a latent image of the sound track on the soundtrack portion of the illm, developing said latent image to metallicsilver and dye images in a color-forming developer, coating the soundtrack portion of the illm.

with a material impervious to subsequent treatment baths, and processingthe film to produce color component images in the remaining portions ofthe film.

9. 'I'he process of forming nent images in registry in two diierentstrata on the same side of a photographic support that comprises formingacolor component `latent image in each stratum by exposing the stratafrom the same side of the support, developing each latent image into asilver image by a process which includes also the development of a colorimage in the lower stratum, subjecting the element for a controlled timeto a bleaching bath containing a retardant for the diffusion thereofwhereby the effect of the bath is limited to the upper stratum and theimage therein is transformed into a developable image, and developingsaid image into a color image of different color than the image in thelower stratum.

10. The process of forming two.color component images in registry intwodifferent strata on the same side of a photographic support thatcomprises forming a color component latent image in each stratum byexposing the strata from the same side of the support, developing eachlatent image into a silver image by a process which includes also thedevelopment of a color image in the lowerstratum, subjecting the elementfor a controlled time to a bleaching bath containing a retardant for thediffusion thereof whereby the effect of the bath is limited to the upperstratum and the image ,therein is transformed into a developable image,and developing said image into a silver image and a color image of adifferent color than the image in the lower stratum, and removing thesilver images from both layers, leaving differently colored images inthe respective strata.

1l. The process of forming two color component images in registry in twodifferent strata on the same side of a photographic support thatcomprises forming a color component latent image in each stratum byexposing the strata from thesame side of the support, transforming eachlatent'image into a silver image by a process which includes also thedevelopment of a color image in the lower stratum, subjecting theelement for a controlled time to a bleaching bath containing a retardant,for the diffusion thereof whereby the effect of the bath is limited tothe two color compoupper stratum and the image therein is transformedinto a developable image, and developing said image into a color imageof different color than the image in the lower stratum.

12. The method of making a color photograph that comprises forming twoimages of silver and dye in different strata on the same side of asupport by exposing the strata from the` same side of th'e support,bleaching only the-outer image in a bath that transform the silver intoa developable salt and decolorizes the we and then redeveloping in asingle step the outer image only into an image of silver and of dye ofdifferent color from the first named dye.

13. The method of making a color photograph that comprises forming twoimages of silver and dye in different strata on the same side of asupport by exposing the strata from the same side of the support,bleaching only the outer image in a bath that transforms the silver intoa developable salt and decolorizes the dye and then redeveloping in asingle step the outer image only into an image of silver and of dye ofdifferent color from the iirst named dye and then removing the silverfrom both images, leaving in the diilerent strata dye images ofdiiferent colors.

14. The process of forming two color com- \ponent images in registry intwo different strata on the same side of a photographic .support thatcomprises forming a color component latent im- 1 age in eachstratumbyexposing the strata from .the same side of the support,transforming both latent images by a single process into images ofmetallic silver and of the same dye by color developing, bathing theouter image only in a bath that transforms the silver image into ametallic salt image and that removes the dye and then treating themetallic salt image to form an image complementary in color to the imagein the inner 15. The method of making a color photograph in an elementhaving sensitized material in layer form on one side of a support, thatcomprises forming two images of the same color in two dierent strata ofsaid sensitized material by exposing the strata from the same side ofthe support, submitting said element to a bath that diffuses into saidmaterial and is capable of decolorizing said images, said bath includinga re tardant for the diffusion thereof, stopping the action of the bathwhen the outer image only has been decolorized and then coloring saidouter image .a different color than the lower layer.

16. 'Ihe process of forming two color component images in registry intwo different strata on the same side of a photographic support thatcomprises forming a color component latent image in each stratum byexposing the strata from the same side of the support, transforming bothlatent images by a common process into images of silver and of the samedye, bathing the outer image only in a bath that transforms the silverimage into a metallic salt image and that removes' affected by saidbath, quickly submitting the photographic element to a bath thatimmediately arrests the action of the first named bath and then treatingthe metallic salt image to forman image complementary in color to theimage in the lower stratum.

17. 'I'he process of producing a colored photographic record on asensitive element having a. plurality of superposedl diiferentlysensitized silver halide layers, which comprises simultaneously forminglatent images in the layers, the images being different color sensationrecords of a subject, simultaneously developing the latent images tometallic silver images, bleaching the plurality of superposeddifferently sensitized silver halide layers, which comprisessimultaneously exposing from the same side to form latent images in thelayers, the images being dllerent color sensation records of a subject,simultaneously developing the latent images to metallic silver and dyeimages by means of a color-forining developer, fixing out the unexposedsilver halide, selectively bleaching at least the outer layer to removethe dye and convert the silver to silver chloride, and redeveloping saidlast-mentioned layer in a color-forming developer. LEOPOLD D. MANNES.LEOPOLD GODOWSKY. Jn.

